EARTH FORMATION POROSITY LOG USING MEASUREMENT OF FAST NEUTRON ENERGY SPECTRUM

摘要

EARTH FORMATION POROSITY LOG USING MEASUREMENT OF FAST NEUTRON ENERGY SPECTRUM (D#74,950-FB) An improved measurement of earth formation porosity is provided by the present invention using measurements of the energy spectrum of fast neutrons. A source of fast neutron is used to irradiate earth formations penetrated by a well borehole. Two neutron detectors, or alternatively a neutron detector and a gamma ray detector, sensitive to neutrons in different energy ranges are spaced at the same effective distance from the neutrons source. Measurements of the fast neutron population at each detector are combined according to predetermined relationships to derive a measurement of earth formation porosity.